Chapter 35: Dysrhythmias Lewis: Medical-Surgical Nursing, 10th Edition

1. To determine whether there is a delay in impulse conduction through the ventricles, the nurse will measure the duration of the patient’s a. P wave. c. PR interval. b. Q wave. d. QRS complex. ANS: D The QRS complex represents ventricular depolarization. The P wave represents the depolarization of the atria. The PR interval represents depolarization of the atria, atrioventricular node, bundle of His, bundle branches, and the Purkinje fibers. The Q wave is the first negative deflection following the P wave and should be narrow and short. DIF: Cognitive Level: Understand (comprehension) REF: 759 TOP: Nursing Process: Assessment MSC: NCLEX: Physiological Integrity 2. The nurse needs to quickly estimate the heart rate for a patient with a regular heart rhythm. Which method will be best to use? a. Count the number of large squares in the R-R interval and divide by 300. b. Print a 1-minute electrocardiogram (ECG) strip and count the number of QRS complexes. c. Use the 3-second markers to count the number of QRS complexes in 6 seconds and multiply by 10. d. Calculate the number of small squares between one QRS complex and the next and divide into 1500. ANS: C This is the quickest way to determine the ventricular rate for a patient with a regular rhythm. All the other methods are accurate, but take longer. DIF: Cognitive Level: Analyze (analysis) REF: 759 TOP: Nursing Process: Assessment MSC: NCLEX: Physiological Integrity 3. A patient has a junctional escape rhythm on the monitor. The nurse will expect the patient to have a heart rate of _____ beats/min. a. 15 to 20 c. 40 to 60 b. 20 to 40 d. 60 to 100 ANS: C If the sinoatrial (SA) node fails to discharge, the atrioventricular (AV) node will automatically discharge at the normal rate of 40 to 60 beats/minute. The slower rates are typical of the bundle of His and Purkinje system and may be seen with failure of both the SA and AV node to discharge. The normal SA node rate is 60 to 100 beats/min. DIF: Cognitive Level: Understand (comprehension) REF: 760 TOP: Nursing Process: Assessment MSC: NCLEX: Physiolog